Collapsible concrete pipe mold



lIuly 20, 1954 P. v. H. SERRELL COLLAPSIBLE CONCRETE PIPE MOLD 4 Sheets-Sheet l Filed March?, 1952 INVENTOR. PETER VHSERRELL p BY /Mt/LQJQU.

/LTTORNEV FlCiy July 20, 1954 Filed March '7, 1952 P. V. H. SERRELL COLLAPSIBLE CONCRETE PIPE MOLD 4 Sheets-Shee 2 FIGB - INVENTOR. 2 PETER \/.H. SERRELL QLCU. M,

A7' RNE? July 20, 1954 P. v. H. SERRELI. 2,683,912

COLLPSIBLE CONCRETE PIPE MOLD Filed March 7, 1952 4 Sheets-Sheet 5 INI/ENTOR.

PETER V H. SER RELL BY 52M A RNEV July 20, 1954 P. v. H. sERRr-:LL

COLLAFSIBLE CONCRETE PIPE MOLD 4 Sheets-Sheet 4 Filed March '7, 1952 INVENTOR. PETER V. H. SERR ELL Patented July 20, 1954 ITED S'l' FFECE 9 Claims. l

This invention relates to a form for casting pipe from a fluent cement concrete and has for its principal objective the provision of a collapsible form or mold which is rigid even when constructed of relativ light material, which is readily assembled and iirmly locked in closed position to receive the fluent material, and which is quickly and readily removable when the casting has hardened to the point at which it is self-supporting.

A purpose of the invention is to provide mold of which the core or inner form may be rolled from a single sheet of relatively light metal plate.

A purpose of the invention is to provide a mold of which the core is truly cylindrical when ei;- panded and which, in that position, has the opposing edges of the longitudinal seam rigidly held with respect both to position and to angular alignment.

A purpose of the invention is to provide the edges of the core, adjacent the longitudinal seam, with stiiiening elements for maintaining the position and the angular alignment of the opposed faces of the seam throughout the length oi the core.

.fl purpose of the invention is to provide both the core and the outer form or casing of which the mold is composed with expanding and contracting means by which each of these movements is produced by a single actuation of a hand lever.

A purpose of the invention is to provide the core with contracting means which iirst break the contact between the metal of the core and inner wall of the inished casting along only de oi the seam, the separation progressing around the inner circumference of the casting the form gradually assumes a spiral contour.

will best be understood with reference to the attached drawings and the fol- '1g description thereof, in which l a vertical, diametric section and in ievation of the assembled mold, showing the core in expanded and the casing in conconcrete;

2 is an elevation of the assembled mold., viewed. the same position as in Fig. l;

Il is a cross-section, as on the line 3 3 of Fig. 1, showing units of a preferred expanding and contracting mechanism in plan, the parts oi the mold being in the position which they assume when the mold is ready for filling with concrete;

Fig. d is a similar section, on the same line as in Fig. 3, showing the parts of the mold in position taken when the mold is ready for rawal from the finished casting;

5 shows a fragment of the core and one unit oi a preferred expanding and contracting means, in elevation;

Fig. 6 is a diagram illustrating the movements, in bringing the core from the expanded to the contracted position, of the links of which the preferred expanding and contracting means is composed;

Fig. '7 is an elevation of one of the units of the casing expanding and contracting means;

Fig. 8 is a vertical section through an alternative form of core expanding and contracting means, as on the broken line il-i of Fig. 9;

Fig. 9 is a plan View or said alternative means, in expanded position, as on the line 3 9 of Fig. 8, and

Fig. 10 is plan View of the same, shown in the contracted position.

Referring rst to Figs. l and 2, the mold consists oi a base plate lil adapted to rest on any level foundation; a casing il resting on an eX- ternal shoulder l2 formed on the base plate; a core I3 resting on an internal shoulder Hi formed on the base plate; a lling funnel i5 resting on the upper end of the casing, and a conical spreader it resting on the upper end oi the core. These units are separable and, when assembled, are retained in position by gravity and by the gripping of the base plate shoulders by the lower ends of casing and core. it is desirable to provide all of these units with ears, lugs or loops ll-l'i for lifting by a light crane or derrick.

The base plate l0 has an upwardly directed and internally tapered flange itl to form the male end of a bell joint, and an outwardly tapered ring i9 around the lower end of the spreader forms the female end of the joint. This end-to-end order may be reversed and, if preferred, these elements may be contoured to form a tongue-and-groove joint.

Referring now to Figs. 3 to 5 inclusive, the core i3, of plate thin enough to be somewhat iiexible but thick enough to be stable against collapse, is provided with a separable, bevelled, longitudinal seam and with inwardly projected stiiening ribs il and 22. These ribs extend approximately the entire length of the core but are interrupted or slotted as at t3 and ifi, at suitable intervals, to admit the expanding and contracting units generally indicated at 25. l'ihese ribs, as well as the brackets hereinafter referred to, may be retained against the inner face oi the core by closely spaced, nat head machine screws, by welding, riveting or combinations thereof. A plurality or units should be provided, the number depending on the length of the mold and the relative stiffness of the sheet from which the core is rolled.

Each unit 2d consists of the following elements: a bracket 2l and a braclret 28 projected in the same general direction from the inner face of the core and from opposite sides of the seam; two pairs of links 29-29 and Eil-Sil connecting these brackets at spaced points and swivelling on pins 3I-3I and LBL-32'; an actuating lever 33 swivelling on a pin 3d which passes through the lower portion of bracket 23, and an actuating link 35, this link swivelling on pin 32 which passes through the lower portion of bracket 2l and on pin 36 which passes through the left end. of lever 33.

The manner in which this linkage functions to open the joint and to contract the core will best be understood with reference to the diagram, Fig. 6, in which the linkage is indicated by heavy lines connecting the pins about which the links swivel. This gure shows the opposed edges 3l and 39 of seam 2) in abutment, as they will be when the form is fully expanded.

When lever 33 is moved in a clockwise direction (as indicated by arrow A) around pin 34 which is carried in bracket 28, pin 36, which is carried in the left hand extension of the lever, is moved to the right (arrow B) as regards pin 34 and to the left (arrow C) ar regards pin 32 which is carried in bracket 2l. Thus the two brackets, and the edges 3'! and 3B of the seam, are urged to move in approximately parallel paths.

Simultaneously, links 29 and 3i) swing counterclockwise (arrows D and E) causing pins 3| and 32, which are carried in bracket 23, to move upwardly around pins 3l and 32', thus tending to elevate edge 31 and relatively depress edge 33, causing the right side of the seam to overlap the left side. The path through which the lower left corner of the right edge travels in overriding the upper right corner of the lower edge is generally indicated by arrow F, but the exact path will be xed by the relative lengths oi the links.

The purpose in giving link 29 a atter initial inclination than link 30 is to cause bracket 23 and the right edge 31 of core I3 to rotate slightly in a clockwise direction with respect to bracket 2'I and the left edge 38, thus inducing a moment in plate I3 which tends to increase its curvature and thereby assists in its collapse.

It will be noted that link 35 and the projecting left end of lever 33 form a toggle which, being on dead center when the core is expanded and the joint is closed, locks the joint rrnly against external pressure. This toggle also exerts maximum contracting force at the beginning of the contracting movement.

As shown in Fig. 4, the core when fully contracted has assumed a spiral cross-section, and the separation of the metal of the core from the inner surface of the casting is much facilitated by progressing circumferentially around the inner wall of the casting as the spiral section develops.

Coordinated movements of the levers 33 of the various expanding and contracting units 2li is produced by afxing their ends to a suitable inember 39, oriented in parallel with the axis of the core and provided with a square head or socket 4G for attachment of an operating lever. Adjustable means such as a set screw 4i with locknut 42 should be combined with each lever 33, so that each toggle will come to rest in the correct position, on dead center or as close to it as ex perience may show to be desirable.

The outer form or casing II has a bevelled, longitudinal seam 43 and a shallow stiiening rib 44 along each side of the seam. One of the stiffeners projects beyond the edge of the seam, as indicated at 45, to form a V into which the opposite bevelled edge nts when the form is closed.

The locking units generally indicated at 46, one of which should be located close to the lower end of the casing and others suitably spaced along its length, consist each of the following elements: a lug 4l and a lug 48 projected from the outer face of the casing and on opposite sides of the seam, each lug being preferably in the form of a yoke; an actuating lever 49 swivelling on pins 5@ which pass through yoke 43, and an actuating link 5I swivelling on a pin 52 passing through yoke 4l and on a pin 53 passing through lever 49. The toggle thus formed locks the opposed edges of the seam firmly together and provides the maximum force for separating the edges when the casing is to be removed from the nished work. Suitable means, such as control of the depth of slot 54 in lever 49, should be provided to ensure that the movement of the linkage is stopped at both open and closed dead center, or at such approximation to it as may be preferred.

As in the case of the core, coordinated movements of the levers 49 are produced by attachment of their ends to a common vertical member 55 having a squared socket 56 for attachment of a wrench or lever.

The lling funnel I5 is supported on the upper end of casting II and may be provided with an internal shoulder or may rest on the lugs I'I attached to the casing. The cylindrical lower end of the funnel should extend far enough down the length of the casing to prevent tipping of the funnel if a charge of concrete should be dumped into it oir center.

The conical spreader I6, which prevents concrete from entering the interior of the core, is provided with an internal shoulder 5l to rest on the upper end of the core, The internal diameter of ring I9, below this shoulder, should be such as to provide a close t with the upper end of the core when the latter is expanded.

To maintain concentricity of the cylindrical elements II and I3 at their upper ends it is desirable to provide a centering spider, which should be located above the upper end of ring I9. This spider may consist of fixed, radial bars joining the funnel and spreader into a single unit, but it is more convenient to handle these elements separately and for that purpose a suitable centering means is suggested in Fig. 1.

In this figure, lugs 5E and '59 are projected toward each other from the funnel and spreader respectively, the ends of these lugs being broadened to form pads which come into sliding engagement when the funnel is set down over the spreader in proper orientation. At least three such pairs of lugs, equally spaced radially, should De provided for accurate centering.

The lower ends of the casing and core being concentrically positioned by shoulders I2 and I4 on the base plate, and both of these elements being inherently stiff by reason of their cylindrical form, they will ordinarily remain concentric throughout their length if the core is centered within the casing at the upper end, as above described. If, however, the length of the mold be excessive in relation to its diameters, it may be desirable to introduce internal stiffening elements into the core, as at SI1-69 in Fig. 3.

The vibration necessary to produce a dense casting may be provided in any known manner, as for example by mounting the assemblies on a shaking table or by attaching a suitable vibrator to either the core or the casing.

Referring now to Figs. 8, 9 and 10, which describe an alternative mechanism for expanding and contracting the core: l3--I3 are fragments of the core shell including a portion of seam 2li, the plate edges adjacent this seam being nurnbered 3l and 38 as in Fig. 3. A single unit of the mechanism is shown, a plurality of such units being disposed at spaced intervals along the length of the seam.

Each unit consists of the following elements: a tongue Eil of heavy plate projected from a lug 62 which is riveted or welded to the inner face of inner edge 3S of the core sheet, the tongue extending over joint ZEE; a pair of parallel spaced plates E53-53 projected from a lugl which is attached to the inner face of the opposite edge 3l of the core sheet, each of these plates being slotted at two locations, as at E5 and 55; a pair of links iii-6i located between plates E53-63 and spanning the end of plate 6l, and a lever 6% located between links l-E'I anal in the plane of tongue 6l.

These elements are operatively connected by: a pin 'it xed in tongue 6l and slidable laterally in slot 65; a pin Se fixed in the extremity of tongue 6| and slidable laterally in slot 5S; a pivot pin lil passing through the extremities of plates 63-63 and lever @53, and a pivot pin 'H passing through links 5?-5'! and through lever 5S at an intermediate point.

As described in connection with Fig. 4, the ends of all the levers 58, which correspond with levers 33 of the preferred form of the unit, are aiiixed to a vertical member 3s which may have a squared head or socket at its upper end. When this member is rotated counter-clockwise, the entire assembly of vertical member and levers pivots around pin iii, i Loving the links of all units sirnultaneously in the contracting direction.

Starting from the expanded position shown in Fig. 9, the swivelling movement of lever 6B around pin it to the position indicated at 6 in Fig. l0, moves pin 'H to position il and links iii-Gl to position Si. lThis movement of the links carries pin Eis through the length of slots Els-B to position t9. As pin to is nxed in plate Si, this plate is drawn toward the right, moving pin "i2 through the length of slots dii-65 to position l2 of Fig. l0.

The movement of the inner edge 3B of seam 2o by which this edge is drawn inwardly and beneath the opposite edge Si are directed and controlled by the torni given to slots SE-. The exact contour given to this slot will vary with the diameter oi the core and the thickness of the plate of which it is composed, but in general terms, the left end of this slot (as illustrated) is given a steeper pitch than the remainder of the length, to cause nrst an abrupt and then a more gradual inward movement of edge 3?.

The contour of slot 5t will be approximately that of slot 551, but the former is placed at a somewhat steeper angle to the core wall in order to impart a slight inward bending moment to the inner edge 33.

It will be noted that in both forms of the core expanding and contracting mechanism the edges 3l and te ci core seam l are positively tained in predetermined relative positions and in predetermined angular relation throughout the expanding and contracting movements.

.in the form nrst described, as in Fig. 6, the brackets El and 23 projected from the two sides of the seam ar connected by rigid links 2Q and Sii, and their rela-tive positions and angles are predetermined by the positions of the linkage ins and the relative lengths of the links.

In the second form, as illustrated in Fig. 9, the two brackets are operatively connected by spaced pins 69 and l2 projected from one oi the brackets and moving in slots 65 and @E formed in the other bracket, the relative positions and angularities of the seam edges being predetermined by the positions of the pins and the contours oi the slots. rhus, in neither form is there any possibility that the seam edges will move in paths other than those fixed in the structure of the linkage means.

assembling the mold to receive a charge of concrete, the core i3, in the contracted position shown in 4 is placed in an upright position on base plate it, and vertical element 39 together with the succession of levers 33 is rotated clockwise until joint is closed as shown in Fig. 3 and the lower end ci the core is expanded into engagement with shoulder ici. The casing il, expanded as shown in Fig. 4, is then placed endwise over the core, and vertical element 55 together with the succession of levers is rotated counterclockwise until the edges of the seam are brought together', as at E in 3. and the lower end of the casing is contracted into engagement with shoulder l2. The funnel l5 and the spreader E@ are then set in position, being so oriented that the tivo pads on lugs 53 and 5s are in contact and the upper ends of the cylindrical elements thus centered. The operation of dismantling is performed by a reversal of the above movements, in order and in direction.

The core structure herein described will be found highly advantageous as regards low cost, ease of manipulation, adaptability to the casting of pipes of large dia-meter, stillness, and conceny with the easing. These advantages are gained mainly through the use of an expanding and contracting mechanism which not only brings the edges of seam into abutment when the core is fully expended, but also provides an eiiective bridge across the seam. When in expanded and locked position the mechanism provides not only continuity for carrying the tangential stresses across the but also provides continuity for carrying moments across the seam, thus preventing the from collapsing inwardly and preventing the inner surface of the casting from going out of round due to external pressure on the core. The carryover of the above functions of the expanding and contracting mechanism between the regions at which the units are located is achieved through the use of stiftening elements 2i and 22.

A further advantage of the above mechanism lies in the fact that it can be so oriented as to provide just enough bevel or that the circumference oi the core is not increased during the initial separation relative movement of t ie edges of the seam, yet the maximum radial movement of the edge El' oi th ,elative the inner face of the casting achieved, thus providing maximum stripping action at the beginning of the collapsing stroke. [it the end of the collapsing stroke the edges of the core are constrained to move in approximate parallelism, thus achieving maximum reduction in diameter of the core. Finally, the relative rotation of the edges of the core induces collapsing moment in the core shell which, in turn, gives more uniform distribution of the increase in shell curvature and aids the stripping action at the eneL of the collapsing stroke,

I claim as my invention:

1. A collapsible core for use in a mold for casting concrete pipe: a cylindrical metallic tube having a longitudinal seam and a plurality of expanding and contracting elements spaced along the length of said seam and connecting the two sides thereof, said elements being so arranged as to cause the edges of said seam to overlap and said core to assume a spiral cross-section when contracted by leading one edge inwardly and substantially circumferentially and to restore the original cylindrical form and to bring the edges of said seam into abutment when said core is fully expanded.

2. In a core for a concrete pipe mold, said core being composed of resilient metallic plate, being cylindrical when expanded and having a single longitudinal seam with faces respectively inwardly and outwardly bevelled and at least substantially in contact when said core is expanded: means connecting opposite sides of said seam for locking together the edges thereof when said core is fully expanded; means for rendering said locking means inoperative and for drawing the edges of said seam in overlapping directions, and guiding means cooperating with last said means to constrain the outwardly bevelled edge oi said seam to move in a curvilinear path inwardly and substantially circumferentially to a position underlapping last said edge, thereby progres sively reducing the circumference of said core during the duration of said movements.

3. In combination with a cylindrical core for a concrete pipe mold, said core having a longitudinal seam with its edges in abutment when said core is expanded; means for expanding and contracting said core, comprising: rigid brackets projected from the inner face of said core on opposite sides of said seam; an actuating lever pivoted on one of said brackets; linkage connecting said lever with the other of said brackets to cause the edges of said seam to move circumferentially with movement of said lever, and means operatively connecting said brackets at spaced points, for guiding the movements of said brackets and said seam edges through predetermined inward and substantially circumferential paths and maintaining at all times predetermined relationships between said edges as to position and as to angular alignment.

4. Structure as described in claim 3, in which the linkage connecting said brackets consists in two pins projected from each said bracket and longitudinally spaced thereon, together with two links each pivotally connecting a pin on one bracket with a pin on the other bracket.

5. Structure as described in claim 3, in which the linkage connecting said brackets consists or" spaced pins projected from one of said brackets and moving longitudinally in slots formed in the other of said brackets.

6. In combination with a cylindrical core for a concrete pipe mold, said core having a longitudinal seam with its edges normally in abutment; means for expanding and contracting said core, comprising: brackets projected from the inner` face of said core on opposite sides of said seam; an actuating lever swivelling around a first point in one of said brackets; a link connecting a second point on said lever with a third point located on the other of said brackets, said points being so disposed that they lie in substantially a straight line when said core is fully expanded and that said iirst and third points are moved toward each other when said second point is moved out of said straight line by movement of said lever, together with a rigidv link swivellng 8 around a point in each said bracket, said rigid link being disposed at an angle to said straight line to cause one side of said seam to move toward and the other side of said seam to move away from the axis of said core simultaneously with said approaching movements.

7. A core for a concrete pipe mold, comprising: a cylinder of metallic plate having a longitudinal seam, the edges of said seam being in abutment when said core is fully expanded, and means for collapsing said core including an actuating lever and linkage associated therewith and with the plate on opposite sides of said seam for moving said seam inwardly and past the opposite edge and for simultaneously reducing the diameter of said core by causing said seam edges to overlap, said linkage maintaining a predetermined relation between both the positions of the edges of said seam `and their angular alignment.

8. A mold for casting concrete pipe comprising a unitary cylindrical casing of resilient plate having a longitudinal seam, means attached to the exterior of the casing for circumferentially expanding and contracting the casing7 those means bringing the edges of the seam into abutment when the casing is contracted, a base plate adapted to support the casing in a vertical position having a, shoulder on which the lower end of the casing is clamped by contraction, a unitary center core of resilient plate having a beveled longitudinal seam and adapted to rest on the base plate and to be clamped thereto by expansion against the shoulder, linking means comprising at least one rigid member hinge mounted in the interior of the core to both sides of the seam for expanding and contracting the core, the linkage means being arranged so as to bring the edges of the core seam into abutment and to restrain the edges of the seam both as to radial position and as to relative angular alignment when the core is fully expanded, to cause the edges of the core seam t0 overlap when the core is contracted by moving one edge relatively inwardly and circumferentiaily with respect to the other edge, and to maintain a predetermined relationship between the positions of the edges of the seam and their relative angular alignment during the contracting movements.

9. In a mold for casting concrete pipe, a cylindrical expansible and oontractable casing and means associated therewith for locking the casing in either the expanded or the contracted position, a tubular core of resilient plate having a longitudinal beveled seam, the edges of the seam being in abutment and the cross-section of the core being circular when the core is fully expanded, and linkage means comprising at least one rigid member hinge mounted to the interior of opposite sides of the seam adapted to move one edge relatively inwardly and circumferentially with respect to the other edge, thereby causing the core to assume a spiral cross-section and shrinking the core to permit its removal from a cast pipe.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 12,586 Shell Dec. 25, 1906 54,518 Field May 8, 1666 310,859 Earl et al Jan. 13, 1885 860,144 Melton July 16, 1907 918,855 Holman Apr. 20, 1909 948,540 Clark Feb. 8, 1910 2,469,629 Boyer May 10, 1949 

